Obama made a quick recovery, claiming that he was making a joke about the University of Kansas basketball coach.

"I was giving Bill Self a hard time. He was here a while back," he said.

Geographical gaffes have not been an uncommon on the campaign trail. GOP presidential candidates Michele Bachmann and Rick Santorum have both tripped over Africa, a continent that contains the nation of Libya.

Campaigning in 2008, Obama said that he'd campaigned in "57 states" while claiming that he'd visited almost all of the 48 continental United States.